I'm a newbie in the µC area but I have some knowledge in programing C++, Java, VB.NET. Last week I bought me an Arduino board with an ATmega168. I'm very surprised of easy programing of the board. But now I have a little problem.
I have to read seven different sensors with the baord. Two of the sensors are proximity sensors(proximity switch) with a NAMUR output(NAMUR: constant voltage and variable current). If a metal part is near (<2mm) the switch, I have an output current of <=1mA. If the metal has a bigger distance than 2mm, I have an output current of >3mA. The voltage is the whole time constant at 8,5V.
My idea now is to convert the current signal to a voltage signal with a transimpedance amplifier(http://en.wikipedia.org/wiki/Current-to-voltage_converter
So I would like to know if somebody has an better and easyier idea how can I measure this signal with my Arduino.
I have attached the datasheet of the sensor below.
I hope my idea is not the only way to measure such a signal.